Power kites add a new dimension to flying kites. These large kites, with a surface area greater than about two square meters, are capable of generating substantial tractive forces. These tractive forces have been used in numerous ways to convert kite flying from an almost sedentary pastime to a fast-paced and challenging sport. For example, athletes and thrill seekers have combined power kites with boards, skis, boats, sleds, and wheeled land vessels to speed across water and land.
The large forces generated by power kites demand significant operator control throughout the flight cycle, especially when the kite is conveying the kite operator. In many cases, the kite is tethered to a hand-held control bar using a fixed-length of kite line. However, the fixed-length system complicates kite launching and subsequent kite control. For example, an assistant may be needed to position and release the kite during launching, and high-traffic areas may produce long periods of waiting for sufficient launching space, or worse, may cause tangled kites lines or injures. Furthermore, fixed-length systems lack the ability to regulate the power of the kite. The operator cannot extend all lines together, in a regulated fashion using a brake mechanism, or sheet the kite, by changing its pitch, and thus power, through altering the relative lengths of the kite lines. A control bar that can vary either the absolute or the relative lengths of kite lengths would provide the operator with an easier, safer launch and greater control throughout the flight cycle.
At least two devices, described in U.S. Pat. No. 5,366,182 to Roeseler et al., and U.S. Pat. No. 6,260,803 to Hunts, include reeling mechanisms that allow the length of kite lines to be varied. However these devices are unsatisfactory for a number of reasons. For example, each device includes an inadequate brake mechanism. These brake mechanisms do not allow the kite operator to feel the rate of line output, and they rely on braking actions separate from steering. Thus, steering the kite may be impaired while attempting to apply the correct amount of drag or brake pressure. Furthermore, these brake mechanisms include mechanical parts that rely on friction. These parts may wear out or work less efficiently when wet. These devices also lack safety features, such as a safety release mechanism to depower the kite, a feature that is available for fixed-line systems. Overall, these devices are not easy to operate, lacking a simple mechanical design with few moving parts. As a result, these devices may result in decreased kite control, more power-kite related accidents, and more device malfunctions. Thus, safer, more efficient, and user-friendly systems for flying power kites are still needed.